Phoenix-area cities rely mostly on dams and reservoirs for their
water needs, but the snowpack feeding those reservoirs was near record
low this year. That means managers are looking to future water supplies
underground.

Flying in a helicopter over Bartlett Reservoir in Tonto National
Forest, Salt River Project surface-water manager Charlie Ester admires
the beauty of the glittering blue lake surrounded by the rocky desert
forest.

“Bartlett is one of my favorite locations, I just love the terrain around it, it’s just a great reservoir,” Ester said.

Even after 35 years of managing the Salt and Verde rivers for SRP,
Ester still is wowed by the water tableau the rivers have carved into
the red desert landscape, as well as the dams humans have inserted into the picture.

“The dam’s really well-behaved as well, it always performs well in a
flood event,” Ester said, speaking of the infrastructure as if it were a
person.

Lately, though, Ester has dealt with more dry years than flood events
as the Valley marches into another year of drought. He said this is the
21st year of the drought; other experts say it’s the 18th.

This year saw a near-record low snowpack, which meant near-record low runoff at only about 100,000 acre-feet of water.

Compare that with 1 million acre-feet the year before, which was an outlier in a record six consecutive dry winters.

That stretch of dry winters, Ester said, “is not only the first time
in our historical record, but that never showed up in the tree-ring
record as well. So in over 800 years, that’s the first time there were
six dry years in a row.”

An acre-foot is a measure of how much water would be needed to flood
an acre of land to depth of 1 foot. Hardly any acre-feet trickled into
Bartlett Lake this year.

“You’ll see that it’s down quite a bit,” Ester said. “Its capacity today is 45 percent.”

Not great, but not worrying, not yet. That’s because SRP augments those low runoff years by pumping groundwater.

Phoenix hedges bets of worst-scenario water crisis with diverse portfolio

“It is really important that we are prepared for any scenario,
including worst-case scenarios,” said Kathryn Sorensen, director of
water services for Phoenix. “Because the consequences of failure are
just too great.”

SRP and Phoenix, as well as several other Valley cities, have pumped
more than a million acre-feet back into the aquifer through the Granite
Reef Underground Storage Project, or GRUSP,
the largest of more than half a dozen recharge sites in the state. SRP
operates a second recharge site in the New River-Agua Fria River area.

“Recharge has been a cornerstone of drought preparation here in the
Valley, and it will continue to be in the future,” Sorensen said.

Think of water-supply options as bank accounts. Reservoirs are like
checking accounts, with city water available immediately and easily.
Underground recharge is like a savings account, where cities take unused
surface water and put it in the ground to withdraw later.

This future use will be especially important when surface water, most likely from the Colorado River, is restricted due to persistent drought.

GRUSP: Elegant acronym for simple aquifer recharge system

Groundwater recharge areas are big, brown fields that SRP
periodically floods so water seeps through the sand and into the water
table hundreds of feet below the surface. Water comes from the Salt and
Verde rivers, Central Arizona Project water and reclaimed water from a
Mesa reclamation facility.

Some call recharging groundwater the “dams of the future.”

“It’s critical that we still have existing use of our reservoirs,”
said Christa McJunkin, water strategy director at SRP, “but you have to
have underground storage because it offers unique benefits.”

One benefit is no loss to evaporation. The geology that makes a site
good for groundwater recharging rests in its composition. The 197-acre
GRUSP is on the ancient bed of the Salt River north of Mesa, where the
rocky, sandy soil are perfect for storing water.

Wwater managers predict other recharge sites will be necessary, but where they should be placed isn’t clear.

“As urbanization happens,” McJunkin said, “you don’t want the best place for a recharge project to be a shopping mall.”

That growth and urbanization is one concern cities are dealing with as water demand creeps up and supply holds steady.

The GRUSP is one option, McJunkin said, of finding new ways to get
more usable water, such as raw wastewater from Mesa and Peoria, into the
system.

“This is one way to bring effluent (wastewater) to use without having
to do the additional, high-level treatment you would need to do if you
were using it directly,” McJunkin said. “The process of the water
infiltrating through the soil takes care of a lot of concerns people
have. You can think of it as a huge filter.”

And with water supplies banked for years, water managers in central
Arizona are optimistic the taps are in little danger of running dry.

- 30 -

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Roosevelt Dam, dedicated in 1911, turned arid Arizona into arable Arizona by controlling the erratic flow of the Salt River and storing the water for irrigation. It also spurred creation of the Salt River Water Users Association, now known as SRP.

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